Electronic amplifier



Sept 12, 19,50 J. DAHLINE 2,522,348

' i ELECTRONIC AMPLIFIER Filed .my 16. 194s' maentor amis/vc; J Mlm/vfPatented Sept. 12, 195() "signor This"inventionrelates "andparticularlyV to thyratron "ampliers ""It is therefore an "object of theririventionto"provide a new and improved type of thyratron arnplir.

f Another:V object. of the .invention is 'ato .i provide an improved.type lof thyratron amplifierfin'iwhich the plate vsupply voltage maybeftaken .directly fromat voltage supplyline of con'imercial-fre-.quency and amplitude.

Another object of the invention is to providel an improved type ofthyratron'arplier Whereinfthe ciruit. y I l ,h advantagederived/from"thistypeofnjlifier construction that theelectronflow'between the control "grid'and c'atho'd'e ofthetiiyratrh is`greatly reduced, The internal cathdetocotrol 1 'grid impedanceof thetriyratronisinparaiiei "with 'the 'cathode resistance of'thefprce'd'in'g j stage and "because the imp'edance i through 1 the'tl'iyratr'on is 'so large "in comparison fwith"y the `cathodeV followerresistance there v' iivill loealn ios't ATrio electron nowiifr'omjthe'Lcontrol gridpfth'e tliyratron. y i k Another'avantage i'sthat the hashproduced will not 'back ,up through the ampliii'e'ribecause of thecomparatively low'im'peidance to ground .through the cathode followerresistance. .This is .of :particular importance in "this Circuit due 150j'the amount of noise produced bythe'thyratron.

AAnother vadvantage isthe' stabilization of the control point ofthe'thyratron because ofitlieA low impedance inputthereto.

' Another object is to provide a cathodefollowe'r circuit wherein-avoltagel to energize a lpreceding circuit is f obtained -frornfthatpotential across the cathode follower resstance.

`Another object f the invention is to provide' a to*H electronictaipiihers 51ooiaims. (cierre-35m .",typesfinlwhicl'ithe resistance ofthe element .varies vviwth ther rlativefhumidity ,of the surroundingiriefdiii'ifn.'= u Y. fl' I ',Tl'i felement" fl! .controlsfthefinputvoltage.. applied to .an -electron...discharge 'device'. in the ffoijr'nio i , 2|`,'fa1`coiitrol girid-2`2, a cathdefZSand aiilament 21.Oheterrninal ofthe .element ill-is connected Vseries with a condenser -IIl.. and grid current initirig*resistorfffzto'the grid. 22. The'terminal .of 'elerneht"I Ulis connectedthrough' ."vdii'cton fifi. andag"resistor,'521i` to 'the 'cathode 23. The .r'esis'toifi#A has asliderZG cooperating'therewith v.to form a` potentiometer, v.the .slider.26. being f 'c"onn'ectedLtlfiroughyy 'a' r`esistor2 5. to the,.-gridterrefinar'fijtiie.girilimitingresisterlsz.'- 1.. 'Po'errortheoperatioii tithe ampiietissiip-:pliei'-by.'.twojpowerTunesie.aride iiea'cung'jto a'rify stabl' urfce fpov/,crimen shown). LineA 8fis 2| "white e"91 is connecter-11h51,conductors priniaryid.. andas'econ'darBd Vhas its secondary vcathodefollower circuit utilizing regenerative "feedback by'means 'of aconnection from the cath- .ode follower resistor tofthe. grid of 'thetube 'in "the'cathodefllo'we stage.

"These and` other Aobjects and advantages 'may become more apparentfrorntlie following, 'more detailed, description taken iin conjunctionwith the drawings in'which:

Figure 1 vshows acircuit embodying vthe pre- -`ierred modification oftheinvention;

Figure v2 shows .a modication 'ofthe .invention ernplo'ying'aA'differentrneans of controllingthe input voltage. y y

Y'In-'the circuitk shown in Figure 1,; the magnitude of the 'input'voltage is "controlleld-bya relative humidity responsive'resistanceelement I 0*. 4elenrieht zna'yfloeV any vone 'of various;Y Well-knownrelay"wifrdiiigcciitg monatl 'while une i9. @05.

The humidity responsive resistance ID, condenser II, grid currentlimiting resistor I2 and resistance 25 are placed across that portion ofresistance 24 between the slider 23 and conductor 54 and receives apotential therefrom.

Operation When the humidity responsive resistance element is at thatresistance value indicating a satisfactory humidity condition thecurrent flow.

through the vacuum tube will be such that the aresult the potential ongrid 22 is sufficiently negative with respect 'to the potential oncathode 23 to cause a very small electron iiow through the tube 20 whichresults in a low potential across cathode resistance 24. This lowlpotential across l the cathode resistance 24 will operate to place asmall potential onthe grid 32 of thyratron 30. i

The bias placed on cathode 33 by transformer secondary 34 tends tooppose the potential placed on grid 32 and the result is that thepotential on the grid 32 is sufiiciently negative with respect to thepotential on cathode 33 to deenergize relay When the humidity isincreased the resistance of relative humidity element I0 is lessened,resulting in a larger current iiow through resistance 25 andconsequently the grid 22 of tube 2U, and

thus the grid 32 of thyratron 30 is driven more knegative and relay 45remains deenergized.

When the humidity in the medium surrounding the relative humidity'responsive resistance element I0 decreases the humidity responsiveelement will increase in resistance value to increasethe total impedancepath across that portion of ,v lresistance 24 between the slider 26 andthe conductor 54 and result in a lower current flowl in the pathcomposed of the relative humidity responsive resistance element Ill,condenser I I, grid current limiting resistor I2, and resistance A25.This will decrease the voltage drop across resistance 25 with the resultthat the grid 22 of tube 20 will be driven in a; positive direction withrespect to its cathode 23. The greater electron flow through tube 20will increase the potential across resistance 24 and raise the potentialon grid 32 with respect to its cathode 33 until tube 3D fires. Thisiiring of tube will energize relay winding and close the relay contacts42 and 43 to place a controlling circuit into operation.

The type of relative humidity responsive re'- sistance element used inthis circuit is one utilizing a salt solution such as is described inthe Dunmore Patent 2,285,421 though it is understood that other types ofhumidity responsive resistl ance elements can be used. Because a saltsolution type of relative humidity responsive resistance is used it isnecessary to place a condenser in series therewith to block the direct'current and prevent the rapid disintegration of thesalt shiftingnetwork intended to aidxin eliminating any chattering tendency of therelay ln the thyratron output circuit. The reason for this is probablydue to the fact that the RC network advances the phasing of thepotential on the grid of the thyratron and thus causes the thyratron tore over a larger portion of the cycle than would otherwise be the case.,y

A condenser 4I is placed inparallel with relay winding 40 to smooth outthe current flowing through winding 40 and further aid in eliJninatingany tendency of the relay winding to chatter. Both transformer primary44 and transformer Y, secondary 34 are tied to power source lead i).This'makes it possible to energize both `tubes and the filamenttransformer from the same source while making use of only one trans-.former witha single secondary winding. Filament 21 of tube 2|] isconnected across the transformer secondary 34 through leads 28, 54, and29. Filament 31 of thyratron 30 is connected across transformersecondary 34 by leads 33 and 39.

I Values of various components Which have been found to worksatisfactorily in the circuit are as follows:

.Resistance I2 megohms 5.0 Resistance 25 megohms 5.0 Resistance 24kilohms 50 Resistance 35 megohms 1.0 Condenser 36 microfarads-- 0.05

with causes most of the current iiow to pass therethrough. This preventsthe thyratron from burning out because of too large a grid current.

Also because or' the comparatively small value of` the cathode followerresistance with respect to the internal cathode to grid impedance 0f thetube in the cathode follower stage any undesired incise from thethyratron which' might otherwise backup through the amplifier will belargely drained olf and so will not affect the operation of the circuit.

Species of Figure 2 I Figure 2 shows a circuit employing a differentmeans of controlling the input voltage.

The overallcircuit in Figure 2 is very similar to that in Figure 1 andlike numerals indicate like components in the two circuits. In Figure 2a photocell i3 replaces the relative humidity responsive resistanceelement I3 .and capacitance II. Photocell I3 has a cathode'I5 and anlanode I6.

Briefly the operation of 4the circuit in Figure 2 is as follows. I YAtthe condition where no light strikes the cathode I5 there 4will be noelectrons emitted therefrom and as a result there will be no currentowing through the circuit. composed of photocell I3, grid currentvlimiting resistor I2, resistance 25 and across lthat 4portion ofresistance 24 between the slider 25 'and conductor 54. vAs a resultthere will be no voltage drop across resistance 25 and grid 22 will besufficiently positive with respect to cathode l23 to permit tube 22 tobe energized. 'Upon energization of` tube 25, grid 32 of thyratron3Ilwill be sufficiently positive with respect to cathode 33 to permitthyratron .30 to lire. Firing of thyratron 3l) energizes relay` winding45', closing contacts 42 and 43 to place a controlling'circulit intooperation.

when a iight is` directsegur() Cathode I5 of 5; phot-,odell IASastreamof electrons Williiow y.from cathode I5 to anode I6 and a currentwill Vflow through resistance 25 to drivethe v.potential-ongri'cllZ-Znegativewith respect to that kpotential on. This ylowering oi thepotentialuon` cathode 23; grid.A 22 deenergizestube 2n, and theresulting potential placed on grid 32 will be=suiiiciently negative toprevent thyr'atron 30 irom--ring.` When tube Sil is de'energizedrelayVdirlisalso 'de-1` energized, permitting contacts .42 :andr to ybreakconnection and open thecontr'olling -i'iircui't-` I f It ni'gl-lt be-noted that Whereas in `Figure '.1 'the condenser Il prevents Aanydirect current `from flowing through the relative humidity element IU tothe grid 22 of tube 20 the -photocell `t3v in Eigur'e'2 prevents anyalternating'current-irofn flowing *to the gr-id 22'. finis-does not,however,-

cnanige kthe characteristics 'of 'the circuit;

t is to be understood thattheli-.nvention herein disclosed is not to beconsidered limited 'to the two-modifications described but rather-to bedefined 'Within thesco'pe of thev appended claims.

`I claim as my invention: v i l' l. n combination: a voltage Source; asignal chargedev'ce including an anode, a control electrcde and acathode; means electrically connecting said voltage source across" thedischarge device; and` impedance in said 'inst-stage; means electricallyconnecting said voltage sourceracrossr the discharge device in saidsecondstage; means electrically connectingl said signal producing devvice to the control electrode'fand across a portion' of the impedance insaid first 'stage in such' a manner 'that the potentialia'cross'sa'idsignal producing device will be derived across a portion'oi saidimpedance; means electrically connecting said impedance between thecontrol electrode and thei'cathode of the discharge device in saidsecondstage to impress a Voltage thereon anda-ricci: energization of thedischarge device in said seon ond stage; and means electricallyconnected to the discharge device in said second stage to utilize theoutput thereof.

2. In combination: source; a signal producing device; a first electronicstage having an electron discharge device including an anode, a controlelectrode anda cathode, and an impedance electrically connected to saidcathode; a second electronic stage having an electron discharge deviceincluding an anode,

a control electrode and a cathode; means electrically connecting saidalternating voltage source across the discharge device and impedance insaid ilrst stage; means electrically connecting said alternating voltagesource across the discharge device in said second stage; meanselectrically connecting said signal producing device to the controlelectrode in said first stage in such a manner that the potential acrosssaid signal producing device will be derived across said poranalternating voltage` kitil tronic stag'efhaving an electronvdischarge.device, including ari-'anode a 'controlelectrode andi-ra;cathode; .andianfimped'ance electrically connected. tofsaidcathode;asecond electronic .stage havingl afthyr-atron. including an anode,l acontrol elecs trod'e and: 'a cathode; means electricallyconnects-5l lofthe thyratron in said second stage; and means electrically connectedto the thyratron in said second stage to utilize the output-thereof.

4. In combination: `"a voltage source;l a signal producing dev-ice;- anelectronic stage having an electron dischargedevice including-an anode;a control-'electrode vand a cathode, and an imped-4 ance electricallyconnected to 'said cathode; `means electrically connecting said voltage"source across the discharge device and impedance in said stage; meanselectrically connecting 'said signal producingdevice to the controlelectrode and across a portion of the impedance in said stage insuch-amanner that the potential across said signal rpro-- ducin'g device willbe derived across a portion'oi said impedance; and "outputcircuitelements connected to said resistor at electrically vspaced points.`

5. In combination; a 'source of alternating voltage; -a humidityresponsivev resistance; an electron discharge device having an anode, acontrol electrode and a cathode; a' first 'resistance electricallyconnectedto said cathode; a second resistance electrically connected'between said" control electrode and a point on said irstresist-y tionof said impedance; means electrically condischarge device in said secondstage; and means electrically connected to the discharge device in saidsecond stage to utilize the output thereof.

3. In combination: an alternating voltage source; a signal producingdevice; a first elecanc'e; means electrically connecting said voltage l"sou'rce 'across said discharge device and said n'rst resistance; andmeans electrically connecting said humidity responsive resistance acrosssaid second resistance and that portion of said first resistance betweensaid point and that terminal connected to said source in such a mannerthat the potential across said humidity responsive resistance is derivedfrom the voltage across said portion of said first resistance.

6. In combination; a source of alternating voltage; a humidityresponsive resistance; an

electron discharge device having an anode, a control electrode and acathode; a first resistance velectrically connected to said cathode; asecond ner that the potential across said humidity responsive resistanceis derived from the voltage across said portion of said firstresistance.

7. In combination; a source of alternating voltl age; a phototube; anelectron discharge device having an anode, a control electrode and acathode; a rst resistance electrically connected to said cathode: asecond resistance electrically con nected between said control electrodeand a point` on said rst resistance; means electrically. connecting saidvoltagesource across said discharge device and said flrstlresistance;and means electrically connecting said phototube across said secondresistance and that portion of said rst resistance between said pointand that terminal. connected to said source in such a manner that thepotential across said phototube is derived from` the voltage across saidportion of said first re-` sistance.

8. In combination; a source cathode; a rst resistance electricallyconnected to. said cathode; a second resistance electrically connectedbetween said control electrode and a pointon said rst resistance; meanselectrically connecting said voltage source across said dis,- Chargedevice and said first resistance; and means electrically connecting saidphototube, in series.

with a current limiting resistance, across said second resistance andthat portion of said first resistance between said pointand thatterminal connected to said source in such -a manner that the potentialacross saidphototube is derived from the voltage across said portion ofsaidv first resistance.

9. In combination: a condition responsive device; an electron dischargedevice having an. anode, a control element and a cathode; a firstresistor electrically connected to said cathode,

said resistor having a wiper arm moving thereacross; means electricallyconnecting an 'alterhating voltage of line potential directly acrosssaid discharge device and said lrst resistor in series therewith; asecond resistor electrically connected between said control element andthe.

Wiper larm associated with s'aid first resistor;

means electrically connecting said condition responsive device betweensaid control element and the terminal of said rst resisto-r distant fromsaid cathode such that the voltage across said condition responsivedevice is derived from the of alternating voltage; a phototube; anelectron discharge de. vice having an anode, a control electrode and aVvoltage across that portion of the first resistcit between the wiper armand that terminal distantfrom .said cathode; a gaseous discharge device`having an anode, a control element and a cath-- ode; means electricallyconnecting anI alternating voltage of line potential across ysaidgaseous discharge device such that the phase of the voltage between theanodes and cathodes of said discharge devices is the same; meansconnecting the cathode of said `first discharge device to the con#y trolelement of said gaseous discharge device through a phase shifternetwork; and a device in' the output circuit of said gaseous dischargede# vice to be energized upon energization of said gaseous dischargedevice.

10. In combination: a voltage source; a photo--v tube; an electronicstage having an electron discharge device including an anode, a controlelec-v rived across a portion of said impedance; and

output circuit elements connected to said resistor at electricallyspaced points.

LAWRENCE J. DAHLINE.

REFERENCES CITED The following references are of record in the lle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,867,398 Cockrell July 12, 19322,160,037 Shepard, Jr May 30, 1939 2,178,985 Blumlein Nov. 7, 19392,299,731 Arendt Oct. 27, 1942 2,413,218 Coroniti Dec. 24, 19462,424,735 Boothroyd July 29, 1947 2.436.762 Turin et al. Feb. 24. 1948

